1. Field of the Invention
The present disclosure relates to a liquid ejection head and a method for manufacturing a liquid ejection head.
2. Description of the Related Art
A liquid ejecting apparatus ejects droplets of liquid from a liquid ejection head and applies the droplets onto a printing medium. Thus, the liquid ejecting apparatus records an image on the printing medium. A liquid ejection head used for existing liquid ejecting apparatuses is illustrated in FIG. 9A.
As illustrated in FIG. 9A, the liquid ejection head includes a substrate 1 and an orifice plate 2 disposed on the substrate 1. In some cases, for example, an interconnecting wire and an insulation layer (neither are illustrated) are formed on a front surface of the substrate 1. Since the interconnecting wire and an insulation layer are very thin, the surface of the substrate 1 is substantially flat and smooth. The orifice plate 2 has an ejection port 3 formed therein. Liquid droplets are ejected from the ejection port 3 due to pressure generated by an energy generating device 4.
In recent years, a liquid ejecting apparatus has been expected to print a high-accuracy image. Accordingly, the ejected droplet of liquid is required to accurately land on the printing medium at a desired position. Thus, a distance d1 between the orifice surface 5 of the orifice plate (an open face having an opening of the ejection port) and a printing medium 6 is decreased so that the liquid droplet landing accuracy is increased.
However, when the distance between the orifice surface of the orifice plate and the printing medium is decreased and if the printing medium deforms, the printing medium is brought into contact with the orifice surface and, therefore, the orifice plate is damaged. Such a case is described below with reference to FIG. 9B. In this case, the printing medium is a sheet of paper. If a sheet of paper is jammed, the shape of the sheet changes. Even when the shape of the sheet of paper changes, the sheet is sometimes continuously conveyed. At that time, as illustrated in FIG. 9B, the sheet of paper is brought into contact with the orifice surface, and the orifice plate may be damaged. Such a problem easily occurs if, in particular, the orifice surface of the orifice plate is close to the printing medium. However, even when the orifice surface of the orifice plate is away from the printing medium by some small distance, such a problem may occur depending on the level of deformation of the printing medium. In addition, in order to produce the liquid ejection head in high accuracy, it is effective that the orifice plate is made of a resin or an inorganic film. However, the hardness of the orifice plate made of a resin or an inorganic film is not so high. Accordingly, if the orifice plate is brought into contact with a sharp sheet of paper, the orifice plate is easily damaged.
Furthermore, as illustrated in FIG. 9C, if the end face of the orifice plate is brought into contact with the printing medium, the entire orifice plate may be peeled off from the substrate.
To solve such a problem, Japanese Patent Laid-Open No. 11-78056 describes a technique in which the orifice surface of the orifice plate is covered by a protective member so that the orifice surface is protected from, for example, a printing medium.